1. Field of the Invention
This invention relates generally to oil well tools, and more particularly drill pipe electrical connectors for rig site applications.
2. Description of the Related Art
In the oil and gas industry, hydrocarbons are recovered from formations containing oil and gas by drilling a well borehole into the formation using a drilling system. The system typically comprises a drill bit carried at an end of a drill string. The drill string is comprised of a tubing which may be drill pipe made of jointed sections or a continuous coiled tubing and a drilling assembly that has a drill bit at its bottom end. The drilling assembly is attached to the bottom end of the tubing. To drill a borehole, a mud motor carried by the drilling assembly rotates the drill bit, or the bit is coupled to drill pipe, which is rotated by surface motors. A drilling fluid, also referred to as mud, is pumped under pressure from a source at the surface (mud pit) through the tubing to, among other things, drive the drilling motor (when used) and provide lubrication to various elements of the drill string.
For many years drilling operations have included instrumentation disposed in one or more jointed pipe sections called a bottom-hole assembly (BHA) near the drill bit to measure various characteristics of the formation, the borehole and the drill string. These measurements are called measurement while drilling (MWD) or logging while drilling (LWD). Measurements from MWD and LWD include formation pressure, properties of hydrocarbons trapped in the formation, temperature and pressure of annulus fluids, drill bit direction, rotational speed and azimuth.
Instruments housed in the BHA and used for the various measurements typically are powered by downhole generators located somewhere along the drill string, and signals from sensors are typically transferred to a mud-pulse telemetry subsystem also located along the drill string. These various components are usually electrically interconnected with insulated wiring also housed within the drill string.
A particular difficult problem exists when wires must traverse more than one joint of a drill string. Achieving and maintaining a reliable electrical bond between pipe joints is very difficult considering the harsh environments encountered downhole, rugged handling of cumbersome pipe joints and time constraints placed on drilling operators at the surface. Prior art devices such as those described in U.S. Pat. No. 3,696,332 to Dickson, Jr. et al., and U.S. Pat. No. 5,251,708 to Perry et al. have tackled this problem using a ring connector with a single and substantially circular contact disposed at opposite ends of a pipe joint. These modular ring connectors are electrically connected together by a bus or wire in the pipe joint. When one pipe joint is connected to the next, a contact ring disposed on each of the mating modular ring connectors electrically mates with a like contact ring disposed a mating pipe or BHA sub thereby establishing an electrical path through the coupled pipe joints or between a pipe joint and BHA sub.
Data acquisition in more recent MWD and LWD devices is becoming more and more sophisticated, and requires more and more power, bandwidth and channels. One of the drawbacks of ring connectors such as those described above is that a single contact and associated bus or wire is a limiting factor on the usefulness of instrumentation used today. Therefore, a need exists to provide a modular ring connector that has multiple contacts and multiple path wiring integrated into a drill pipe and the various BHA subs attachable thereto. Also, in providing an improved modular ring connector having multiple contacts, a further need exists to verify that the multiple contacts and associated conductors are mated properly.
The present invention addresses the drawbacks discussed above by providing a drilling apparatus and method for transmitting an electrical signal between an uphole location and a downhole location using modular electrical connectors having multiple contacts and multiple wiring pathways integral to a drill string pipe joint.
An apparatus is provided for conveying electrical power and data signals between a first location and a second location in a well borehole. The apparatus comprises a first drill pipe disposed at the first location, and a second drill pipe disposed at the second location. A second end of the second drill pipe is coupled to a first end of the first drill pipe. A first plurality of conductive pathways such as insulated wires extend longitudinally through at least a portion of the first drill pipe and terminate at the first end. A second plurality of conductive pathways extend longitudinally through at least a portion of the second drill pipe and terminate at the second end. A verification device is operatively associated with the first and second pluralities of conductive pathways for verifying electrical continuity between the first and second pluralities of conductive pathways.
The present invention also provides a method for conveying electrical power and data signals between a first location and a second location in a well borehole via multiple conductive pathways. The method comprises coupling a first end of a first drill pipe to a second end of a second drill pipe. The two pipes are conveyed such that the first drill pipe is conveyed to the first location and the second drill pipe is conveyed to the second location. The first and second drill pipes have corresponding pluralities of conductive pathways extending longitudinally through at least a portion of each drill pipe and terminating respectively at the first and second ends. The method provides for verifying electrical continuity between the first and second pluralities of conductive pathways with a verification device operatively associated with the first and second pluralities of conductive pathways to ensure the pathways are electrically connected.
A modular ring connector provided by the present invention connects multiple independent electrical wireways upon coupling of pipe joints or of a pipe joint and BHA sub. The ring connectors may include four segments made of conductive material, and with segments centers at an angle of 45xc2x0. Segments made of non conductive material are disposed between the conductive segments, and the nonconductive segments also have centers at an angle of 45xc2x0.
The alignment of conductive segments or contacts may be accomplished by various embodiment options including time cut thread, ring alignment and electrical selection. A time cut embodiment includes a pipe joint and/or a BHA sub having all threads of a pin and/or box end with modular connector cut to precise specifications. The multiple contacts on the connector ring will then always align when the threads are connected to a like-threaded connector.
A ring alignment embodiment includes an alignment gauge. During assembly of the modular ring the position of the thread to the shoulder will be measured by the gauge. The gauge will show the correct position of the segments, and when assembled into the sub, the ring will be positioned with respect to this measured position.
The third and most viable option is electrical selection where the segments are aligned by an electrical switching device. When the system is powered, the electronics will automatically measure the position of each independent modular ring at each thread and will align the contacted wires according to the measurement.